From: Fujii Masao <fujii@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: psql: Avoid returning oom_buffer from psql slash command scanner
Date: Wed, 19 Aug 2026 03:40:06 +0000
Message-ID: <E1wwX9o-000000019S6-4BZf@gemulon.postgresql.org> (raw)
psql: Avoid returning oom_buffer from psql slash command scanner
psql_scan_slash_command() builds the command name in a local
PQExpBufferData and returns the buffer's data pointer to its caller. If
either the initial allocation or a later enlargement failed, that data
pointer could be the static PQExpBuffer OOM buffer rather than malloc-owned
storage. HandleSlashCmds() could then eventually pass it to free(), causing
undefined behavior.
Detect a broken command-name buffer before returning it, report OOM, and
return NULL instead. Teach HandleSlashCmds() to treat a NULL command name
as a command error before trying to compare or dispatch it.
Backpatch to all supported versions.
Reported-by: Junwang Zhao <zhjwpku@gmail.com>
Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Junwang Zhao <zhjwpku@gmail.com>
Discussion: https://postgr.es/m/CAHGQGwEh3R3=1tx_a5=fTDJ+ycuwxWMEn6bG_Yt4B5P+hE7AVw@mail.gmail.com
Backpatch-through: 14
Branch
------
REL_19_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/9d4505b7f826b649501253c094aea5c28a66f266
Modified Files
--------------
src/bin/psql/command.c | 4 +++-
src/bin/psql/psqlscanslash.l | 15 +++++++++++++--
2 files changed, 16 insertions(+), 3 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: fujii@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: psql: Avoid returning oom_buffer from psql slash command scanner
In-Reply-To: <E1wwX9o-000000019S6-4BZf@gemulon.postgresql.org>
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